1. Field of the Invention
The present invention relates to an infrared sensor apparatus for detecting an infrared heat source such as a human body.
2. Description of the Related Art
FIG. 1 is a view showing a conventional infrared sensor apparatus. In this infrared sensor apparatus, one Fresnel lens 2 as an infrared lens is arranged for one infrared sensor 1 on the incident side of the sensor 1. This Fresnel lens 2 defines, e.g., a plurality of infrared detection areas A to D.
However, in this infrared sensor apparatus, for example, when an infrared heat source such as a human body enters the infrared detection areas A to D, the Fresnel lens 2 condenses infrared radiation from the plurality of areas, thereby detecting the infrared heat source with one fixed infrared sensor 1. In this case, only the presence/absence of an infrared heat source or movement thereof is detected. A variety of information such as the position, the moving direction, and the moving speed of the infrared heat source can hardly be detected in detail.
To detect information from an infrared heat source in detail, a method is proposed, in which the fixed infrared sensor 1 and the Fresnel lens are mechanically moved to form the plurality of detection areas A to D.
In another infrared sensor apparatus, as shown in FIG. 2, a plurality of infrared sensors 1A to 1D are utilized. The condensing portions of the Fresnel lens 2 are disposed in correspondence with the infrared sensors 1A to 1D, thereby individually detecting infrared radiation from the detection areas A to D.
In the method of mechanically moving one infrared sensor 1, however, a moving unit, a movement control unit, and the like are required, resulting in a bulky and complicated apparatus. When the plurality of infrared sensors 1A to 1D are used, as in FIG. 2, the condensing portions of the Fresnel lens 2 must correspond to the infrared detection areas A to D. In this case, since a large lens is used, highly precise manufacturing of the lens becomes very difficult, and images may be blurred in some regions of the lens. Additionally, the apparatus becomes bulky and expensive.